Soft seat retention

ABSTRACT

A device, such as a valve, having a soft seat disposed in a groove formed in and circumferentially along a hard seating surface of a hard seat and one or more retaining elements disposed in the groove in contact with the soft seat and the hard seat.

BACKGROUND

This section provides background information to facilitate a betterunderstanding of the various aspects of the disclosure. It should beunderstood that the statements in this section of this document are tobe read in this light, and not as admissions of prior art.

The present disclosure relates generally to wellbore operations andequipment and more specifically to actuation devices for downhole tools(e.g., subsurface tools, wellbore tools) and methods of operation.

Hydrocarbon fluids such as oil and natural gas are produced fromsubterranean geologic formations, referred to as reservoirs, by drillingwells that penetrate the hydrocarbon-bearing formations. Once a wellboreis drilled, various forms of well completion components may be installedin order to control and enhance the efficiency of producing fluids fromthe reservoir and/or injecting fluid into the reservoir and/or othergeological formations penetrated by the wellbore. In some wells, forexample, valves are actuated between open and closed states tocompensate or balance fluid flow across multiple zones in the wellbore.In other wells, an isolation valve may be actuated to a closed positionto shut in or suspend a well for a period of time and then opened whendesired. Often a well will include a subsurface valve to prevent orlimit the flow of fluids in an undesired direction.

SUMMARY

A device according to one or more aspects of the disclosure includes ahard seat having a hard sealing surface that extends circumferentiallyabout an axial bore and has an inner circumferential edge and an outercircumferential edge, a soft seat disposed circumferentially along thehard sealing surface between the inner and the outer circumferentialedges. The device may include a groove formed in and circumferentiallyalong the hard sealing surface between the inner and outer edges, thesoft seat positioned in the groove and having a soft sealing surfacepositioned above the hard sealing surface. One or more retainer elementsmay be disposed in the groove between the soft seat and the hard seatfor example to wedge the soft seat into connection with the hard seat.

An example of a well system includes a valve disposed with a tubularstring and deployed downhole in a wellbore, the valve including a hardseat having a hard sealing surface extending circumferentially about anaxial bore, a soft seat disposed circumferentially along the hardsealing surface between inner and outer circumferential edges of thehard sealing surface, and a flapper having a flapper sealing surfacecooperative with the soft seat to provide a seal when the flapper is ina closed position. In accordance to some embodiment the soft seat ispositioned in a groove in the hard sealing surface with one or moreretainer elements disposed in the groove in contact with the soft seatand the hard seat.

An example of a method includes disposing a valve in a tubular string ina wellbore, the valve including a hard seat with a hard sealing surfaceextending circumferentially about an axial bore, a soft seat disposedcircumferentially about the hard sealing surface between inner and outercircumferential edges of the hard seating surface, and a flapper havinga flapper sealing surface cooperative with the soft seat to provide aseal when the flapper is in a closed position.

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofclaimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with standard practice in the industry, variousfeatures are not drawn to scale. In fact, the dimensions of variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 a schematic of a well system incorporating an embodiment of adownhole valve utilizing soft seat which is retained according to one ormore aspects of the disclosure.

FIG. 2 is a sectional view of a valve incorporating a hard seat and asoft seat cooperative with a curved flapper according to one or moreaspects of the disclosure.

FIG. 3 is a schematic illustration of soft seat retained with a curvedhard sealing surface according to one or more aspects of the disclosure.

FIG. 4 is a schematic illustration of a valve showing a groove formedalong a hard sealing surface according to one or more aspects of thedisclosure.

FIGS. 5 and 6 illustrate positioning of retainer elements to hold a softseat with a hard seat according to one or more aspects of thedisclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the disclosure. These are, of course,merely examples and are not intended to be limiting. In addition, thedisclosure may repeat reference numerals and/or letters in the variousexamples. This repetition is for the purpose of simplicity and clarityand does not in itself dictate a relationship between the variousembodiments and/or configurations discussed.

As used herein, the terms connect, connection, connected, in connectionwith, and connecting may be used to mean in direct connection with or inconnection with via one or more elements. Similarly, the terms couple,coupling, coupled, coupled together, and coupled with may be used tomean directly coupled together or coupled together via one or moreelements. Terms such as up, down, top and bottom and other like termsindicating relative positions to a given point or element may beutilized to more clearly describe some elements. Commonly, these termsrelate to a reference point such as the surface from which drillingoperations are initiated.

Subsurface valves are commonly actuated to a first position (e.g., open)by the application of hydraulic pressure, for example from the surface,and biased to the second position (e.g., closed) by a biasing mechanism(stored energy assembly), such as an enclosed pressurized fluid chamberor a mechanical spring. The fluidic pressure may be applied to a pistonand cylinder assembly, for example, that acts against the biasing forceof the biasing mechanism to open and hold the valve opened. The biasingforce acts on the piston to move it to a position allowing the closuremember to move to the closed position when the actuating fluid pressureis reduced below a certain value.

Examples of some subsurface valves are disclosed in U.S. Pat. Nos.4,161,219 and 4,660,646 and U.S. Patent Application Publications2009/0266555, 2010/0006295 and 2010/0139923, which are all incorporatedherein by reference.

FIGS. 1-6 illustrate embodiments of a device, generally denoted by thenumeral 12, incorporating a soft seat 32 and a retainer 34 according toaspects of the disclosure. Device 12 has an inside diameter 7 definingan axial bore 36 through a hard seat 38 having a hard sealing surface40, a flapper 30 is pivotally coupled to the hard seat (e.g., housing)to move between an open position and a closed position. By coupled, itis understood that flapper 30 may be directly coupled to hard seat 38 orindirectly coupled by an intermediate member. For example, flapper 30 isdepicted pivotally connected by a hinge, for example pivot pin 31. Hardsealing surface 40 is cooperative with a flapper sealing surface 42 toprovide a seal when flapper 30 is pivoted to a closed position. Hardseat 38 is generally described herein as being constructed of a metalmaterial (e.g., carbon steel, stainless steel, etc.) and the hardsealing surface 40 and the flapper sealing surface 42 creating ametal-to-metal seal. Hard sealing surface 40 may comprise a non-metalmaterial, such as a ceramic or other substantially non-pliable material.

Device 12 includes a soft seat 32 providing a pliable sealing surface 33that is cooperative with the flapper sealing surface 42 for example toeffect a better seal to gas flow relative to the hard sealing surface40. A retainer 34 may be utilized to maintain soft seat 32 in positionrelative to the hard sealing surface when the flapper 30 is in the openposition.

FIG. 1 is a schematic of a well system 10 incorporating an embodiment ofa downhole tool 12 having a soft seat 32 according to one or moreaspects of the present disclosure. Depicted well system 10 includes awellbore 16 extending from a surface 18 and lined with casing 20. Atubular string 22 is disposed in wellbore 16. Downhole tool 12 isdepicted in FIG. 1 as non-limiting embodiment of a subsurface flowcontrol device (e.g., valve) connected within tubular string 22 forselectively controlling fluid flow through the tubular device 12 andtubular string 22. For example, subsurface valve 12 may be used to blockthe flow of reservoir fluid 2 through tubular string 22 to the surfacewhen fluid 2 flows from formation 4 through tunnels 6 and into wellbore16 and tubular string 22 under a greater pressure than desired.

Depicted valve 12 is operated in this example to an open position inresponse to a signal (e.g., electric signal, fluidic signal,electro-fluidic signal, mechanical signal) provided via control system24. Depicted control system 24 includes a power source 26 operationallyconnected to actuator apparatus 14 to operate a closure member 30 (e.g.,valve member, flapper) from the one position to another position. InFIG. 1, the closure member 30 is in a closed position blocking fluidflow through the bore of the tubular string 22. In the non-limitingembodiment depicted in FIG. 1, control system 24 is a fluidic (e.g.,hydraulic) system in which fluidic pressure 26 is provided throughcontrol line 28 to actuator apparatus 14 which applies an operationalforce that moves the actuator apparatus in a first direction engagingand actuating closure member 30 to an open position allowing fluid intubular string 22 to flow across closure member 30. Hydraulic pressureis maintained above a certain level to hold the closure member 30 in theopen position. To actuate subsurface valve 12 to the closed position, asshown in FIG. 1, the hydraulic pressure via control line 28 is reducedbelow a certain level. As is known in the art, the hydraulic pressure isreduced below the level of the force that biases the closure member 30to the closed position.

Referring specifically to FIGS. 2-4, soft seat 32 is for example acircular member formed of a pliable and/or low yield material such as,and without limitation, TEFLON, polyetheretherketon (PEEK),polytetrafluoroethylene (PTFE), other plastics and non-plastics such aspure nickel. In accordance to embodiments the soft seat 32 has a uniformthickness so that that is expands uniformly when heated. The hardsealing surface 40 is formed circumferentially about the bore 36 and hasan inside circumferential edge 41 and an outer circumferential edge 43.A groove 44 is formed into the hard sealing surface 40 between theinside and outside edges 41, 43 and extends the circumferentially lengthof the hard sealing surface. The groove may be cut normal to the contactsurface or along the longitudinal access.

In FIGS. 2-4 the flapper 30 is a curved flapper and the hard sealingsurface 40 is curved and undulates along the perimeter between crestsand valleys. The soft seat 32 may be utilized in a flat flapper designsas well. Traditional curved flapper valves that include both a soft seatand a hard seat utilize a two piece connection where the soft seat isconnected for example along a peripheral edge of the hard seat byanother hard seat or housing section. Cutting a groove 44 into the hardsealing surface 40 provides a stable pressure bearing surface.

When the flapper 30 is in the open position the soft seat 32 is retainedin the groove 44 and in connection with the hard seat 38 by retainer 34which is disposed in the groove 44 between the soft seat 32 and the hardseat 38 to wedge or squeeze the soft seat 32, below the soft sealingsurface 33, into contact with the hard seat 38. The retainer element 34may be located between the soft seat 32 and the inner circumferentialedge 41 (i.e., on the inner side of the soft seat) or between the softseat and the outer circumferential edge 41 (i.e., on the outer side ofthe soft seat). The retainer element 34 may take various forms, such asan elongated member, e.g. a wire, or a set of two or more elements suchas spherical balls.

In some embodiments, the retainer element 34 may be disposed partiallyin an undercut groove 46 formed below the hard sealing surface 40 andbetween the groove 44 and the structural hard seat 38. The undercutgroove 46 may be formed on the outer side of the groove 40 and soft seatand extend through the hard seat 38 to an opening 48 formed in theexterior surface 50 of the hard seat 38 for positioning the retainer orretainers 34 in the undercut groove.

FIG. 5 illustrates positioning a retainer 34, in the form of anelongated member such as wire in the undercut groove 46 to extend aroundthe full or substantially full circumferentially length of the soft seat32. The elongated retainer 34 is fed through the opening or port 48 ofthe undercut groove 46.

FIG. 6 illustrates positioning spherical retainers 34 in the undercutgroove 46 to secure the soft seat in position. A spherical retainer 34is inserted through port 48 into the undercut groove 46 and into contactwith the soft seat 32. The soft seat 32 may rotated in the groove tomove the first spherical retainer 34 circumferentially. A secondspherical retainer 14 can then be fed through the port 48 into theundercut groove 46 and the soft seat 32 and second spherical retainerrotated circumferentially. The process can be repeated until the desirednumber of spherical retainers 34 are positioned in the undercut groove46 and around the circumference of the soft seat 32.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the disclosure.Those skilled in the art should appreciate that they may readily use thedisclosure as a basis for designing or modifying other processes andstructures for carrying out the same purposes and/or achieving the sameadvantages of the embodiments introduced herein. Those skilled in theart should also realize that such equivalent constructions do not departfrom the spirit and scope of the disclosure, and that they may makevarious changes, substitutions and alterations herein without departingfrom the spirit and scope of the disclosure. The scope of the inventionshould be determined only by the language of the claims that follow.

The term “comprising” within the claims is intended to mean “includingat least” such that the recited listing of elements in a claim are anopen group. The terms “a,” “an” and other singular terms are intended toinclude the plural forms thereof unless specifically excluded.

What is claimed is:
 1. A device, comprising: a hard seat comprising ahard sealing surface extending circumferentially about an axial bore andhaving an inner circumferential edge and an outer circumferential edge;and a soft seat disposed circumferentially along the hard sealingsurface between the inner and the outer circumferential edges.
 2. Thedevice of claim 1, wherein the hard sealing surface is curved.
 3. Thedevice of claim 1, wherein the soft seat is a circular member formed ofa pliable material.
 4. The device of claim 1, wherein the soft seat ispositioned in a groove formed in the hard sealing surface.
 5. The deviceof claim 1, further comprising: a groove formed in and circumferentiallyalong the hard sealing surface between the inner and outer edges, thesoft seat positioned in the groove and having a soft sealing surfacepositioned above the hard sealing surface; and a retainer elementdisposed in the groove and in contact with the soft seat and the hardseat.
 6. The device of claim 5, wherein the retainer element is disposedbetween the soft seat and the outer circumferential edge.
 7. The deviceof claim 5, wherein the retainer element is an elongated member.
 8. Thedevice of claim 5, wherein the retainer element is an elongated memberextending circumferentially or substantially circumferentially along thelength of the soft seat.
 9. The device of claim 5, wherein the retainerelement comprises two or more elements spaced circumferentially apart.10. The device of claim 1, further comprising: a groove formed in andcircumferentially along the hard sealing surface between the inner andouter edges, the soft seat positioned in the groove and having a softsealing surface positioned above the hard sealing surface; an undercutgroove formed below the hard sealing surface along circumferentiallyalong the groove; and a retainer element disposed in the groove and incontact with the soft seat and the hard seat.
 11. The device of claim10, wherein the hard sealing surface is curved.
 12. The device of claim10, wherein the retainer element is an elongated member.
 13. The deviceof claim 10, wherein the retainer element comprises two or more elementsspaced circumferentially apart.
 14. The device of claim 1, furthercomprising a flapper having a flapper sealing surface cooperative withthe soft seat to provide a seal when the flapper is in a closedposition.
 15. A well system, comprising: a valve disposed with a tubularstring and deployed downhole in a wellbore, the valve comprising: a hardseat comprising a hard sealing surface extending circumferentially aboutan axial bore and having an inner circumferential edge and an outercircumferential edge; a soft seat disposed circumferentially along thehard sealing surface between the inner and the outer circumferentialedges; and a flapper having a flapper sealing surface cooperative withthe soft seat to provide a seal when the flapper is in a closedposition.
 16. The system of claim 1, wherein the flapper is a curvedflapper and the hard sealing surface is curved.
 17. The system of claim15, further comprising: a groove formed in and circumferentially alongthe hard sealing surface between the inner and outer edges, the softseat positioned in the groove and having a soft sealing surfacepositioned above the hard sealing surface; and a retainer elementdisposed in the groove and in contact with the soft seat and the hardseat.
 18. A method, comprising: disposing a valve in a tubular string ina wellbore, the valve comprising: a hard seat comprising a hard sealingsurface extending circumferentially about an axial bore and having aninner circumferential edge and an outer circumferential edge; a softseat disposed circumferentially about the hard sealing surface betweenthe inner and the outer circumferential edges; and a flapper having aflapper sealing surface cooperative with the soft seat to provide a sealwhen the flapper is in a closed position.
 19. The method of claim 18,wherein the flapper is a curved flapper and the hard sealing surface iscurved.
 20. The method system of claim 18, wherein the valve furthercomprises: a groove formed in and circumferentially along the hardsealing surface between the inner and outer edges, the soft seatpositioned in the groove and having a soft sealing surface positionedabove the hard sealing surface; and a retainer element disposed in thegroove and in contact with the soft seat and the hard seat.